Type J is superior in every aspect. -compact, you can fit 3 plugs into an outlet while Type F only fits one for example. -robust. -cannot reverse polarity. -no fuse required as the law requires proper fuses in every electric installation with law enforced periodical checks. -round pins that cannot puncture your skin if you step on them. It's hard to face the pins upwards anyway.

sometimes it's their hidden basement they're discovering.